I noticed that : $builder ->add('myRadios', 'choice', array( 'choices' => array( 'one' => 'uno', 'two' => 'due'), 'multiple' => false, 'attr' => array('class' => 'testClass'), 'expanded' => true so attr with class is not rendered: the output is: http://pastebin.com/cAqLx9XZ PS: When i use attr on other field ex. text with same procedure class appears properly. plz help. thx